It is useful to know certain characteristics of a borehole for drilling operations. In order to gather info about the borehole, drillers often use wireline or logging while drilling (LWD) tools that retrieve data and produce logs or even images representing the characteristics of the formations penetrated by the borehole. Gathering data can be done using a variety of logging tools. Some logging tools measure a number of geological characteristics including density, porosity, resistivity, magnetic resonance, and formation pressure. These logging tools are used as part of a logging system.
Logging systems used for logging earth formations can include wireline operated logging tools and wireless logging tools. Typically, wireless logging tools are battery powered and are provided with an electronic memory for storing the logging data. After conducting a logging run, the tool is retrieved to surface where the logging data are read out from the electronic memory.
One problem relating to the use of wireless logging tools is that during logging no information is available to the operator with regard to the functioning of the logging tool. For example, in case the logging tool is not correctly deployed in the borehole during the logging operation, the operator will notice the incorrect deployment only during read out of the electronic memory. Notice of this incorrect deployment may not be discovered until after one or more logging runs have been carried out. In such unfortunate situations, valuable drilling rig time is lost, especially when one is required to re-run the logging tool in the same wellbore interval. In addition, some circumstances may prevent re-running the logging tool in the same wellbore interval, leading to the loss of useful logging data for the interval.